Northstar Engines and System Technical Discussion Discussion, 4.6 N* Cylinder walls in Cadillac Engine Technical Discussion; Just started a N* rebuild and after removing the heads noticed some blued areas in a couple of cylinders
Likely ...

Re: 4.6 N* Cylinder walls

A cylinder block overheat would be about 1,100 degrees too cold to 'blue' a cylinder wall. The head gasket failure was due to head bolts pulling from the compromised cylinder block bolt holes. That's why you need to insert or stud all 20 bolt holes.

If the original cylinder wall cross hatching is still evident, clean the cylinders thoroughly with lacquer thinner, apply a coat of synthetic engine oil and install a new set of rings spec'd for the engine. These engines almost never need honing and almost never leave a step at the top of the piston ring travel - check it out with a fingernail scraped up the cylinder walls. Be dead SURE to install the new ring set according to instructions - including the second compression ring: dot up.

Study the GM service manual concerning cylinder walls, wall finish, why not to hone, engine overhaul and other such mundane Northstar stuff. A good check of the cylinder roundness and taper will tell you whether the block is serviceable.

Read through the sticky posts just above these recent threads - ^^^ . Study the Cadillac Technical Archive way up ^^^ in the top black bar.

Re: 4.6 N* Cylinder walls

i just like the looks of the second motor
it came apart so much better. Even the head bolts were evenly torqued no
aluminum/oil on bolts. The first engine about half of bolts were loose, real mess, oil everywhere YUCK
Took a day to clean even before disassembly.
At this point just thinking about new rings for the second block.
What's a good cleaner for the pistons?
Any thoughts?

Re: 4.6 N* Cylinder walls

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[/COLOR]that's a for sure!
I pulled all the pistons out of the second block, cross hatch looks good, rings were definitely in bad shape.
Planning to rering, replace rod bolts, likely new rod bearings, head stud kit and gaskets.
I was able to pull the pistons without separating the block halves...just don't want to mess with the lower end, it was sealed up nicely, virtually no leaks.
Will there be a problem just reusing the crankshaft bolts? And i'm hoping to reinstall pistons without splitting block.
Sure it would be easier, but like i said don't want to go there.

So Where do I Go From Here????

I bought a '97 Eldorado from a salvage with minor body damage and a head gasket leak.
No big deal right? Change gaskets, studs...whtever.
I dropped the engine out the bottom, with the help of a FSM...easy.
Turns out the engine has a cracked cylinder so i scrapped it.
Picked up a '99 engine that was all carbonned up (old man motor never driven over 30mph)
Engine was less intake, exhaust manifolds and front cover.
Sure clean it up, change rings, rod bearing and bolts, and put together. Right?
Ya sure.
Now it turns out that the pistons and heads are different from one year to the next.
'97 engine (block stamped '96) pistons have reliefs cut in them '99 does not
heads are different, intake and exhaust ports are different
manifolds just aren't going to work if i swap
Can i buy new pistons with reliefs and use them in the '99 block?
Do i just build the '99 block and find the right manifolds, and change a few sensors?
At this point i'm scratching my head.
Any thoughts would help